Use-After-Free Vulnerability in libcurl Affecting HTTP/2 Streaming

CVE-2026-10536

What is CVE-2026-10536?

CVE-2026-10536 is a use-after-free vulnerability discovered in libcurl, a widely used library for transferring data with URLs, which supports multiple protocols including HTTP, HTTPS, and HTTP/2. This specific vulnerability arises when an application utilizes the HTTP/2 stream-dependency configuration options, CURLOPT_STREAM_DEPENDS or CURLOPT_STREAM_DEPENDS_E, and then proceeds to invoke curl_easy_reset(). Following this reset, if the handle is terminated using curl_easy_cleanup(), libcurl attempts to access an internal data structure that has already been freed, leading to potential memory corruption. Such vulnerabilities can severely disrupt the operation of applications that rely on libcurl, potentially allowing unauthorized actions that compromise the integrity and availability of services or data.

Potential impact of CVE-2026-10536

1. Memory Corruption: The use-after-free nature of this vulnerability can lead to memory corruption within the application, which may result in crashes or unpredictable behavior. This instability can make affected applications unreliable and lead to denial-of-service scenarios.

2. Data Leaks: Exploitation of this vulnerability could allow attackers to read sensitive information from memory, which may include user credentials, API keys, or other confidential data inadvertently exposed by the corrupted memory structure.

3. Unauthorized Actions: Through careful exploitation, an attacker may leverage this vulnerability to execute unauthorized commands or actions within the application context, potentially allowing them to bypass security controls or escalate privileges within the system.

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